Use of n-acyl sarcosines in miscible flooding



United States Patent 3,212,575 USE OF N-ACYL SARCOSINES IN MISCIBLE FLOODING Henry B. Fisher and Dixon W. Peacock, Bartlesville,

0kla., assignors to Phillips Petroleum Company, a corporation of Delaware No Drawing. Filed Mar. 12, 1962, Ser. No. 179,225 8 Claims. (Cl. 166-9) This invention relates to the recovery of petroleum. by a miscible fluid flood. In another aspect the invention relates to a miscible fluid flood in which an oil-soluble surfactant is contained in the miscible flooding agent.

In another aspect the invention relates to a miscible flgi d. flogd in which an oil-glublaSlLtfiactant is contained in the miscible flogdipg agent and wa t er is psed to displace the agentt'h'rfiirgh the reservoir. "'In' another aspect, the invention relates to improved miscible flooding agent comprising an oil-soluble surfactant and a hydrocarbon solvent.

Secondary recovery of petroleum from underground reservoirs by flooding the reservoirs with a miscible flooding agent has undergone extensive development and trial. For an efficient flooding operation, it is important that the contained petroleum fluids in the reservoir be displaced as completely as possible, and that as large a portion of the miscible agent as possible be recovered. A factor in the eflicient displacement of the petroleum fluids is the displacement of connate water from the reservoir by the flooding agent, thereby releasing a larger portion of the contained petroleum fluids. In many instances natural gas is utilized as the miscible agent displacement fluid. However, because of its cost, and because high reservoir pressures must be maintained to maintain miscibility with the miscible flooding agent, and because of its low viscosity, which tends to lower reservoir sweep efficiencies, it is highly desirable to utilize water as a substitute for the gas as a final driving fluid. Water is relatively cheap and has a viscosity (or mobility) which can lead to more favorable reservoir sweep efficiencies. Lack of miscibility with the usual flooding agents, such as liquefied petroleum gas (L.P.G.), however, obviates the use of a simple water drive because of the high residual saturation of the miscible flooding agent.

An object of this invention is to increase the displacement of contained petroleum fluids in a miscible fluid flood.

Another object of this invention is to obtain minimum flooding agent residual saturation in a miscible fluid flood.

Other aspects, objects and the advantages of our invention are apparent in the written description, the drawing and the claims.

According to our invention, petroleum is recovered from an underground reservoir by injecting a slug of a miscible flooding agent containing a surfactant in solution, and driving the flooding agent through the reservoir to recover the contained petroleum and flooding agent by following with a quantity of water. A miscible fluid flood normally involve-s injecting 3 to 10 percent of a pore volume of LPG. or its constituents into a reservoir and displacing the slug to the producing well by means of the final gas drive. According to our invention water is substituted for the gas as the final drive and an oil-soluble surfactant is used in the flooding agent to increase the displacement of connate water, and thus increase the production of SEARCH petroleum fluids, while still maintaining a desirable level of flooding agent residual saturation, resulting in economical operation of the process.

Further, according to our invention, from .001 to 2 weight percent, preferably .01 to 0.1 weight percent, of a hydrocarbon soluble surfactant is added to the miscible flooding agent. A particularly useful surfactant of this type is a commercial surfactant, Sarkosyl-O, of Geigy Industrial Chemicals, which contains oleoyl sarcosine as the active ingredient, the active ingredient being contained as percent and over in the surfactant composition.

Other related surfactants comprising N-acyl sarcosines also are valuable in the practice of our invention, as for example, lauroyl sarcosine, cocyl sarcosine, and stearoyl sarcosine.

Further, according to our invention, there are provided improved miscible flooding agents comprising a hydrocarbon solvent and an oil-soluble surfactant. Preferred flooding agents include one of the N-acyl sarcosines, especially N-oleoyl sarcosine, dissolved in a hydrocarbon solvent, preferably from .01 to 0.1 weight percent of the flooding agent being the surfactant.

Other specific surfactants found to be useful include reaction products of nonyl phenol and ethylene oxide of the type specifically Igepal CO-61O of Antara Chemicals in which 11:7-9; reaction products of tertiary t-octyl phenol and ethylene oxide, of the type C5 1? (OCHzCHzh-OH Miseible Petroleum and Flooding Agent Flooding Agent Recovery Inlet Well Outlet Well Underground Petroleum Reservoir As shown in this diagram, a misgiigflggdipg agent is injected into the reservoir through an injection well. The flooding agent contains a surfactant in solution, as explained above. Following the injection of the flooding agent in the desired amount, water is injected into the input well to drive the flooding agent through the reservoir. The contained petroleum and the flooding agent are recovered from an output well of the reservoir.

Reasonable modification and variation are possible within the scope of our invention which sets forth a process for producing petroleum from an underground reservoir by miscible flooding, including use of an oil soluble In the following examples flooding was performed 5 surfactant in the flooding agent and improved miscible in a sand-packed tube, the tube being one inch in diameter flooding agents, comprising a hydrocarbon solvent and and 30 inches long. Flooding liquids were pumped at a an il l bl f t t known constant rate with a positive displacement pump We claim; through the Sand pack to a separator. The eflluent 1 A process for recovering petroleum from an under.- were collected and measured in graduated cyhnders. The ground reservoir comprising the Steps of: water phase was delomfzed Water Whlle phase was injecting into an injection well a volume of a flooding nheptane or a Somme of surfamant i i agent miscible with said petroleum in the range of 129F130 i sand well k was used In the 001mm 3 to 10 percent of the swept pore volume of said While flooding rates of 32 cc. per hour for the solvent fl t t f 001 flood and 10 cc. per hour for the water flood produced a reservoul Sal 00 mg agen con ammg. q satisfactory balance of viscous and capillary forces in the 9 2 welgllt Percent of an N'acyl sarcosme m sand pack. An upstream pressure of 12.5 p.s.i. was main- F 9 thefemi tamed throughout the tests dr1v1ng sald flood ng agent through sa1d reservo1r to an To minimize the effects of gravity, the flooding was per- Output Well y ll'llectlng a q lf 0f Watfif Sufficlent formed in vertical columns and the Water was flooded up- 20 to drive Said flooding agent to sald Output W611; and wardly and the heptane downwardly. The dry weighed recovering Petroleum and saidfioodillg agent from Said column was saturated by evacuating and flooding slowly Output well. 'x, with acetone under reduced pressure so that any trapped 2. Tlie process of claim 1 wherein said flooding agent air was replaced by water-soluble vapors. This was folcontains from .01 to 0.1 weight percent of an N-acyl lowed by a large quantity of water, more than enough to sarcosina remove all of the acetone. The water-saturated column 3 A process fo recovering petroleum f o an d was weighed and the pore volume calculated from the ground reservoir comprising the steps in Permeablhty was calculate? by injecting into an injection well a volume of a flooding Justmg the Posmve dlsplacemT'nt Pump dehver at a agent miscible with said petroleum in the range of known rate to the column wh1le measuring the pressure 3 to 10 percent of the swept pore Volume of Said drop across h sand pack The water'satmttd column reservoir, said flooding agent containing from .001 was flooded w1th the heptane, or with the solution of sur- 2 ht t f 1 M f t t factant in heptane until water production stopped, to to Welg percen 0 2111.0} 6 sur ac an lected from the rou cons1st1n of lauro lsarcoslne establish the heptane saturation. Saturanons 1n all 1ng p g y stances were determined by measuring the volumes of the 3 cocPyl sarcosme Stearoyl Sarcosme and oleoyl produced fluids. Following the establishment of heptane F9 saturation, the column was water flooded until no more dnvmg 531d floodlng agent through sald reserve to an heptane was produced. The volumes of produced fluids Output Well by lnlectlng a q y of Water Sufficient were again measured and the saturation was calculated. to drive Said flooding agent to Said Output W611; and Table I shows flooding rates, surfactants used and data recovering petroleum and Said flooding agent from Said obtained. output well.

Table I O Saturation 0 Residual 0 Recovery Pore 01 Water Sand K Vol- Flood Flood Surfactant Darcys ume, Rate, Per- Rate, Per- Percc. 0c./l1r. 00. cent ccJhr. 00. cent 00. cent P.V. P.V.

120-230 0. 85 156 32 100 64.2 10 26.5 17 73.5 73.5 120-230-.- 0. 85 156 82 122 78.2 10 24.5 15.7 98 80 Triton X-45. 120-230 0. 85 156 32 114 73.3 10 29.8 19.1 84.2 74 Igepal 00-610. 120-230 0. 85 156 32 142 91.0 10 20.4 13.1 121.6 85.5 Sarkosyl-O. 120-230.-. 0. 85 156 32 114 73.3 10 29.0 18.6 85 74.5 Alkaterge-C. 120-230 0. 85 156 32 90 57.7 10 25.9 16.6 64 71 120230 0.85 156 32 118.2 75.8 10 27.2 17.4 91 76 Vietamul-89. 120-230 0.85 156 32 132 84.7 10 28 17.9 104 79 Agent TEF-l.

From the data of Table I it is seen that in all instances 4. The process of claim 3 wherein said flooding agent the surfactants enabled a higher heptane saturation to be contains from .01 to 0.1 weight percent of an oil-soluble obtained, thus indicating more complete displacement of surfactant. connate water which is favorable to more complete recov- 5. The process of claim 3, wherein said flooding agent cry of petroleum products in the reservoir. The inis liquefied petroleum gas. creased heptane saturation was obtained with a slight in- 6. A process for recovering petroleum from an undercrease in residual heptane saturation in three instances, ground reservoir comprising the steps of: no appreciable increase or decrease in two instances. It injecting into an injection well a volume of a flooding is noted that use of one of the surfactants, Sarkosyl-O agent miscible with said petroleum in the range of resulted in a very greatly increased heptane saturation 3 to 10 percent of the swept pore volume of said and at the same time a significantly decreased residual reservoir, said flooding agent containing from .001 saturation, indicating a very substantial increase both in to 2weight percent of oleoyl sarcosine; petroleum recovery and recovery of miscible flooding driving said flooding agent through said reservoir to agent. an output well by injecting a quantity of water suf- In this application, the expression miscible flooding is ficient to drive said flooding agent to said output used to mean one in which the displacement of the oil well; and in place is accomplished by the use of a flooding agent recovering petroleum and said flooding agent from said which is miscible with the oil. output well.

5 7. The process of claim 6 wherein said flooding agent contains from .01 to 0.1 weight percent of oleoyl sarcosine.

8. The process of claim 6, wherein said flooding agent is liquefied petroleum gas.

References Cited by the Examiner UNITED STATES PATENTS 2,790,779 4/57 Spivack et a1 252-392 2,812,817 11/57 Sayre 166-9 2,875,831 3/59 Martin 166-9 3 ,082,822 3/63 Holm et a1. 166-9 6 FOREIGN PATENTS 459,039 12/ 36 Great Britain.

OTHER REFERENCES BENJAMIN HERSH, Primary Examiner. BENJAMIN BENDETT, Examiner. 

1. A PROCESS FOR RECOVERING PETROLEUM FROM AN UNDERGROUND RESERVOIR COMPRISING THE STEPS OF: INJECTING INTO AN INJECTION WELL A VOLUME OF A FLOODING AGENT MISCIBLE WITH SAID PETROLEUM IN THE RANGE OF 3 TO 10 PERCENT OF THE SWEPT PORE VOLUME OF SAID RESERVOIR, SAID FLOODING AGENT CONTAINING FROM .001 TO 2 WEIGHT PERCENT OF AN N-ACYL SARCOSINE IN SOLUTION THEREIN: DRIVING SAID FLOODING AGENT THROUGH SAID RESERVOIR TO AN OUTPUT WELL BY INJECTING A QUANTITY OF WATER SUFFICIENT TO DRIVE SAID FLOODING AGENT TO SAID OUTPUT WELL; AND RECOVERING PETROLEUM AND SAID FLOODING AGENT FROM SAID OUTPUT WELL. 